The invention relates to a fire-resistive glazing having two or more preferably transparent sheets of glass, at least one of which is a glass which will not shatter upon an abrupt temperature rise due to exposure to fire.
A large variety of double glazings and multiple glazings are known which contain two or more panes of glass arranged in parallel. Such multiple glazing serves primarily for thermal and sound insulation purposes. However, there is as yet no insulating multiple glazing which provides fire protection in the sense that shattering will not occur when it is exposed to fire.
Multiple glazings are known which do offer fire protection properties which are achieved by using wire glass in one of the panes. Such wire glass panes shatter like any normal window glass in the event of a fire, but the fragments are so held together by the wire fabric contained in the pane that to some extent they prevent the passage of smoke and flame through the shattered window.
In addition to the fact that wire glass shatters in a fire, it has the additional disadvantage that, in any case it does not possess complete transparency and consequently its use is often unacceptable for esthetic and architectural reasons. Its use is limited largely to industrial structures.
Multiple glazing has become known through German "Offenlegungsschrift" No. 2,220,523, which contains one pane made of glass ceramic as the fire-resistive pane. Such assemblies are usually too expensive for use in the glazing of windows in building construction, and furthermore the production of completely transparent ceramic window glass is possible only with difficulty. Since windowpanes made of glass ceramic are not glass panes in the strict sense of the word, they are not to be understood as glass windowpanes in the meaning of the invention.